This fixes the `deco_rect` and `rect` properties in the IPC responses
to match i3's behavior.
`deco_rect` should be relative to the parent node, not the current
node. This also takes tabbed and stacked decorations into account and
will calculate `deco_rect` for all containers since tabbed and stacked
child containers will have decorations.
`rect` should exclude the window decorations.
According to the i3 ipc documentation, `window_rect` excludes the window
decorations from the calculation. This just clarifies that in
`sway-ipc.7.scd`
This add `sway-ipc.7.scd` that documents the IPC protocol.
This also increased the minimum scdoc version from 1.8.1 to 1.9.0 to
allow for table cells to be continued on the following line